The Epidemiology and Biostatistics Core is a key component of the renewal application because it coordinates information about other: infant dyads from the past and the current period. These mother-infants pairs include the past cohort (n=316) and the current cohort (n=306). The Core is responsible for the design and analysis of a number of clinical and animal studies in this proposal. Collection, handling, shipping, storage and tracking of milk, saliva, serum, and stool specimens are tasks of this Core. Dr. Morrow leads this Core and is the senior epidemiologist and biostatistician. Dr. Morrow leads this Core and is the senior epidemiologist and biostatistician. Dr. Morrow is assisted by Dr. Mekibib Altaye. The Project Coordinator at the Cincinnati site is Jareen Meinzen-Dett, MOPH, who is responsible for data management and analysis. At the Mexico site, Dr. Guerrero is the field investigator responsible for study design, data management and analyses. Dr. Guerrero must assure that the samples are obtained in a timely and current manner. The samples from the cohort in Mexico must also be processed and stored properly before shipment.